Rear disc conversion and brakes upgrade

[Wild E. Coyote]

The ABS is functinal in both cases. The devil is in the detail: the gap to rings has to be exactly 0,6 mm if you want the ABS to work as it should (i.e. not trigger unnecessary). And it is easier to setup using the second method that will be posted.
Cheers

 

[Wild E. Coyote]

Ok, here it is. So, the basics are the same: hubs need machining down to accomodate different ABS tone rings, but that is about it. Everything else can be done at home using a drill, tap and dremel!

Comparison of both solutions: the old with recess of about 2 mm for the sensor to sit in

The newer one which doesn't need that (big) recess

Instead of enlarging the opening of tone ring to match that of focus', you just put the ring on top covering the dust shield for the bearings as well

This is extremely important: make your tool for pressing the ring on. It is very simple

I just had it machined with ID of 68,3 mm

If you bend just one notch, the ABS will work erradically

Closeup of a ring

In order to be able to slide the hubs onto the spindles, I had to take away the rubber seal at the bottom (that is the downside of this method)

Using the hubs from the drums I made this tool for the exact positioning of the sensor. On my first attempt one of my sensors was off by 1 mm (radially) and the ABS would pass self test but at slowing down would kick in and grind. The positioning of the sensor is extremely important try not to improvise there!

This tools enables you to put the sensor on the right (I guess you'd call it nearside) wheel to the other side of spindle. If you do it like that, then you can keep the angled sensors and put on the spacers if you like!

You just turn the tool the other way around and you have the exact position for the RW

I guess you all know what this is. I don't know the name in English, we call them spies (why don't ask me). 0,6 mm is the one we are after!

At the start you will have a gap of about 1,5 mm so you will have to take about 0,9 mm of material

Of course, I have to admit I had a spare rear wheel ABS sensor (thanks to Pumanoob, thanks a million, mate!) what enabled me to measure everything on the table instead of lying under the car!

Then used a dremel and started to hone down the hub where sensor is going to sit. Regulary checked the gap to the ring using 'a spy 60' until have reached the desired thickness of material. Drilled a hole, tapped it (you need a 5 mm drill and M6 tap) and that was it.

The exact and same gap on both sides is important for the ABS to operate correctly; it can tolerate some differences, but it will operate unnecessary if gap is not exactly 0,6 mm.

 

[tuonokid]

bump

 

[jimfrp88]

Very good write up here, very useful! :thumbs:

I'm also considering this conversion.. For anyone who has done it already, what should I expect to pay to get the rear hubs lathed?

Cheers

 

[XAF]

Don't know if it was a good or bad price, but just got mine back the other day. Fully machined up hubs and stubs, tone rings fitted and gapped, sensors ready to plug in for £150 delivered

 

[tuonokid]

Hi James
Doesn't sound too bad that as there's a ton of work doing it yourself.
Barry

 

[jimfrp88]

I've got time to play about with mine as I won't be using it over winter.
So ideally I just want to get the hubs lathed.
Personally I think anything more than £40/£50 will be too much.

 

[tuonokid]

Hi Jim
It's not so much the work on the hubs as the work on the back of the stub axles that's a pain to do. It took me ages to get mine right as I did them by hand.
Barry

 

[jimfrp88]

Hi Barry.
If you were to give this conversion a number out of 10 for testing your patience, 10 being your blood boiling?
I don't mind doing things like this, I've researched the conversion and got the time and the knowledge, hence why I'm considering it. But if I'm going to end up swearing and losing my temper with it I don't think I'll bother.

 

[tuonokid]

Hi Jim
I'm totally patient when I'm working on things but this was a lot of messing about as I got a mate to lathe up the hubs but I had to file out for the sensors, recess the back of the axles with a dremmel, drill and tap the back of the axles etc. Compared to stuff other people do it was straightforward but the hubs/axles had to come off many times before I got the sensor gap right. I would give it a 6 but it was well worth it for me as the puny drums would look stupid behind my 17" wheels and the handbrake is fantastic now + no leaky rear cylinders.
Barry

 

[jimfrp88]

Thanks for that Barry.

I did think about skimming the entire rear face of the hub down by 2mm and going from there.
Would you advise that or would that be comprising the strength of the hubs?
Cheers.

 

[tuonokid]

Hi Jim
Do you mean skimming down the entire rear face of the STUB AXLE by 2mm? I would definitely advise against that as I think the stub axle may be an interference fit in the casting.
Barry

 

[jimfrp88]

Fair enough, Barry k:

Like I said I'm only thinking about it so we'll see what happens.

But on a positive note, I have decided that at some point I will be upgrading to ST front brakes.. Rude not to considering it's a straight swap for an instant improvement :thumbs:

 

[tuonokid]

Hi Jim
Yeah if you've got big enough wheels on the front it's an easy swap but remember to get the caliper carrier bolts with your purchase as they are 12mm rather than 10mm. When I did mine I had a selection of imperial and metric drill bits so I could increase the size of the holes through the hub arrangement steadily rather than go straight from 10 to 12. the other thing to watch out for is the bracket that holds the flexi hose as that will not match where the caliper is. No probs with ABS, though :thumbs:
Barry

 

[Wild E. Coyote]

Barry, I think you misunderstood Jim. He is planning on ST front disc conversion, and I assume that would mean fiesta ST150? If that is so, no drilling needed, it si simple bolt off, bolt on job, really...

Regarding the rear conversion: JIm, get one faulty rear sensor and then you can do all the work on your table and be precise with it as I have shown. If you do it like that, and provided the positioning of your sensors is right (jusing the stub axle as guide) it will work right away

 

[tuonokid]

Hi Sinisa
I was assuming he meant ST170 Focus but I did think that the ST150 would have used 12mm bolts as well. Oh and sorry for hijacking your excellent post
Barry

 

[jimfrp88]

Sorry guys, I should have made that clear.. yes I was referring to the Fiesta ST front brakes.
I have some on order and providing the weather holds up that will be my task for one day thistles weekend.

With regards to the rear disc brakes, I've had a quote for getting the rear hubs machined down.. And at £85 I feel that's too expensive when you take the cost of everything else in to account.
So unless I can find someone to do it cheaper I'll be sticking to the drum brakes. :'(

 

[tuonokid]

Hi Jim
Is that just machining the hubs or doing the work on the stub axles as well? You need an old man in a shed, ask your mates there must be someone locally who'll do it for £50 cash (not a business).
Barry

 

[jimfrp88]

Yes, Barry. That's just to machine the hubs. I can do the stub axles myself.

I've been asking around but nobody seems to know anyone.

If it's going to be this much hassle I'll just stick to drums ha :lol:

 

[tuonokid]

Hi Jim
That's a massive rip off as it's the easiest part of the conversion to do!
Barry